Regulation mechanism of melanin production by related-genes and UV.

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Contents of pheomelanin and its precursor, 5-S-cysteinyldopa in culture media from agouti (C57BL/10JHir-A/A) melanocytes was increased by L-tyrosine compared with black (a/a ; CS7BL/10JHir) melanocytes. Moreover, pheomelanin content in the epidermis from 3.5-and 5.5-day-old A/A mice was much higher than a/a mice. The A gene was expressed in the A/A dermis of 0.5-, 3.5-and 5.5-day-old mice, but not in the a/a dermis as well as in the A/A and a/a epidermis. These results suggest that pheomelanin production in the epidermis from 3.5-and 5.5-day-old A/A mice is induced by the expression of the agouti gene in the dermis.The study using melanocyte culture system of newborn mice wild-type at the pink-eyed dilution (p) locus (black ; C57BL/10JHir) and from congenic mice mutant at that locus (C57BL/10JHir-p/p) showed that the proliferation of p/p melanoblasts/melanocytes was stimulated by L-tyrosine (Tyr), and that the differentiation of melanocytes was induced by L-Tyr as the age of the donor mice advanced, even though eumelanin and pheomelanin failed to accumulate in p/p melanocytes and were released from them at all ages of skin development.Moreover, the study using melanocyte culture system of newborn mice wild-type at the slaty (sit) locus (black ; C57BL/10THir) and from congenic mice mutant at that locus (C57BL/10JHir-slt/slt) or of newborn mice wild-type at extension (e) locus (black : C57BL/10JHir) and from congenic mice mutant at that locus (C57BL/10JHir-e/e) showed eumelanin synthesis was inhibited in slt/slt melanocytes, and that both eumelanin and pheomelanin were synthesized in epidermis and dermis and their synthesis increased in e/e epidermis and dermis as skin development proceeded.